Purine Derivatives Enable Tin Perovskite Solar Cells With Over 0.9 V Open‐Circuit Voltage and 13.8% Efficiency

Recently, the development of lead‐free perovskite solar cells has attracted considerable attention. However, in tin halide perovskites, Sn 2+ is prone to be oxidized to Sn 4+ , which leads to the occurrence of p‐type self‐doping in the perovskite, high defect density, and nonradiative recombination, thus severely restricting the open‐circuit voltage ( V oc ) and efficiency. To address this, 6‐thioguanine (TG) and 2‐aminopurine (2‐AP) were introduced into the perovskite precursor. The experimental results showed that the V oc of the target device with TG has significantly increased from 0.80 to 0.92 V, and the power conversion efficiency (PCE) has also risen from 11.04% to 13.84%. In addition, the TG device can maintain approximately 87% of their initial PCE after being stored in an N 2 atmosphere for 1400 h. This work provides an effective approach to simultaneously enhance the performance and stability of tin halide perovskite solar cells through molecular coordination strategy.